Research into application methods and adhesives
Lars Carlsson (2013) Makeup-FX.com Silicone prosthetics part 3 SD. [online] Available from: https://www.youtube.com/watch?v=zjXAKa0aGrw#t=227 [Accessed: May 2nd 2015]
Notes:
- You can make a bald cap out of gelatine - he brushed gelatine over a rubber latex bald cap
- mixing parts A and B of platgel 10, you can apply this to the face (using a non-latex sponge) and apply a silicone prosthetic straight over this. can blend the edges with more of the silicon and use a damp sponge. Advantages with the silicone is theres no solvents in it, so you can put it right under the eye, as it wont harm the model. Wipe it out of any eyelashes etc. The model must remain totally still during this process though, or the silicone will distort.
- You can add a retarder so that you have ore working time with the silicone
- Used silicone glue on the neck and chin area, as the
All following images: fxwarehouse n.d. [online] Available from: http://www.fxwarehouse.info/mm5/merchant.mvc?Screen=CTGY&Store_Code=FW&Category_Code=ALLFSM [Accessed: May 9th 2015]
I've recently heard that Pros-aide is only really meant for use on encapsulated pieces, as pros-aide is water-based and silicone is the only thing that really sticks to silicone.
It doesn't mention this in the desciption, so I don't know whether its common knowledge or something you learn with experience or maybe just a preference for some people.
I like how reliable Telesis 5 sounds, that it will keep prosthetics on during strenuous conditions. As its silicone based, I would imagine its also more comfortable for the actor when applying around the eye area.
The no-tack pro-aide also sounds like a much better alternative for PAX paint rather than normal pros-aide.
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piece kept coming off. If it came off with this adhesive, the actor could just push it back on. This glue sticks immediately, whereas you have more movement and working time with the platgel
- platgel 10 on a q-tip to seal the edges, like bondo. Could also thicken the silicone with cab-o-sil
- press over this with a damp (non latex) sponge
- removal process with silicone is so much easier, as the silicone adheres to the prosthetics, so they basically peel off the face.
- These are injected silicone pieces. He didn't say if they're encapsulated or not, but i'd assume not. He pre-painted all the pieces.
- He didn't want to put platgel on the lips and used silicone glue instead
- He said that silk screen paints also work really well as another option instead of skin illustartor. They can also be airbrushed
- greasepaint makes edges really visible and is very hard to remove oncef applied
Kryolan (2015) Silicone Adhesive. [online] Available from: https://us.kryolan.com/product/silicone-adhesive-strong-bond-30-ml [Accessed May 9th 2015]
I assume this is what Lars meant when he mentioned silcone glue. The desciption also describes it as spirit gum and says it can be removed with silicone adhesive remover.
"Allow to briefly dry and press object onto place"
"Used for the effective adhering of facial appliances"
Kryolan (2015) Hydro Spirit Gum. [online] Available from:https://us.kryolan.com/product/silicone-adhesive-strong-bond-30-ml [Accessed May 9th 2015]
"Hydro Spirit Gum is an adhesive for make-up artists, containing no solvent, with water base. Hydro Spirit Gum is effective in adhering objects for short periods of time, and for holding down hair and eyebrows before they are covered with a bald cap or plastic film. Use a brush to apply Hydro Spirit Gum and allow to dry slightly before adhering the required hair or objects. Since this is a water-based preparation, Hydro Spirit Gum dries slowly. Warm air can be used to speed up the drying process. This product can be easily removed with soap and water."
This product sounds a bit pointless to me. 'Short periods of time' indicates that it doesn't last long and I can't see why you wouldn't want the assurance of an adhesive lasting a long time. Also the fact that it takes a long time to dry just sounds really inconvenient and impractical for applying a makeup quickly.
Premier Products Inc. n.d. [online] Available from: http://www.ppi.cc/artsci3.htm [Accessed: May 9th 2015]
Premier Products Inc. n.d. [online] Available from: http://www.ppi.cc/artsci_adhesives_thinners.htm [Accessed: May 9th 2015]
These are all products I've never heard of and from their descriptions, i'm not entirely sure what they're meant to be used for.
The beta bond sounds good because it can be mixed with water, alcohol and acrylic paints and it dries clear. I don't know what it means by acrylic-based, and I don't now if its intended purposes are for silicone prosthetics, foam etc......
The sigma bond is advertised as working will for adhering platium silicone prosthetics and postiche pieces with 'superior strength and comfort'. I imagine this is a fairly good product, as its a similar price to Telsis 5.
I've also read a lot of good reviews of this product and think it would be a good investment for my kit.
CrownBrushBeauty 2013. Ve Neill - How to apply a Silicone Prosthetic [online] Available from: https://www.youtube.com/watch?v=u_IwOng8Rbo [Accessed: May 9th 2015]
In this video, Ve Neill used thinner Telesis to apply a small encapsulated piece. It stuck down immediately.
She also used IPA to blend the edges and then acetone, as she said that was most effective to blend away the edge of the baldiez.
Can seal piece with pros-aide
I'd never heard of this method before or even thought of it as an idea. I wish I'd known about it before my assesment, as I would've experimentrd with it more and it probably would've helped my application process. I don't think that he was working with encapsualted pieces though, as he didn't blend any edges. I don't know if this platgel method would work as well for GFAs, as they'd have the cap plastic coating so it wouldn't be silicone on sillicone adhesion.
- Pros-aide, bondo or cabopatch can be stippled or applied with q-tip to help blend edges
- DUO false eyelash glue can also be used
- cap plastic edges can be dissolved with IPA, witch haxel or acetone
- if silicone edges need re-working or have folded over, then telesis thinner can be used to swell the silicone so that you can re-position them
Debrecini, T. 2013 Special Makeup Effects. Oxon: Focal Press
Neils Materials 2014. [online] Available from: http://www.neillsmaterials.co.uk/product/snappy-g/ [Accessed: May 10thh 2015]
"One of the best silicone adhesives for adhering prosthetics appliances to skin. I swear by this adhesive. Its incredibly strong and I’ve never had an actor suffer any kind of reaction to it. The solvent used is very safe and slow drying. I know some people don’t like it being a little slower but I prefer it as I get time to position or re-position my piece. There’s also a trick to speeding up the drying. Firstly don’t apply it too thick. You only need a thin layer anyway so it’s a good habit to get in to. When you brush the adhesive on to the skin continue to brush back and forth over it. This brushing really forces the solvents out fast making the adhesive tack up very quickly. Snappy G is what is know as a pressure sensitive adhesive. This means that for the best bond you should try and get adhesive on both the back of the appliance and on the skin, let them dry, and then press them together. This contact adhesion will create the strongest possible bond."
So unlike just using platgel 10, this silicone adhesive has solvents in it, which means it will still be sensetive around areas like the eye. Many reviews say it is compareable to Telesis, as they both take a little while for the glue to tack up so you have a slightly longer working time with it. Snappy G is also cheaper than telesis,
Model Mayhem 2010 [online] Available from: http://www.modelmayhem.com/forums/post/640010 [Accessed: May 10th 2015]
I'm still trying to research information on caulking, as I don't know what it is and theres no mention of it in Todd Debrecini's book.
This was a forum discussing whether you could make cheap, castable silicone from caulk, which seemed to be a bad idea and a dangerous suggestion.
From my research, caulking seems to be any kind of silicone based window/bath sealant. It can definately be used for painting silicone pieces but should not be used to make or apply the pieces.
Srewfix 2015 [online] Available from: http://www.screwfix.com/p/unibond-silicone-frame-sealant-brown-300ml/47623?kpid=47623&cm_mmc=Google-_-Product%20Listing%20Ads-_-Sales%20Tracking-_-sales%20tracking%20url&kpid=47623&cm_mmc=Google-_-Shopping%20-%20Sealants%20and%20Adhesives-_-Shopping%20-%20Sealants%20and%20Adhesives&gclid=CjwKEAjwg7yqBRCu5NmlgMm6i08SJADDEudZFW-OWLscGIbUgOyUeE3PKybK-vuDSdV8pmba76A2ExoC6eDw_wcB [Accessed: May 10th 2015]
I came across a website along my research that had some extremely thorough information on silicone in general, which I thought would be really useful to have even for future reference.
Lynch, D N. 2011. The How and WHy of Silicone [online] Available from: http://naomidlynch.com/2011/05/29/the-how-and-why-of-silicone-part-1/ [Accessed: May 10th 2015]
The How and Why of Silicone. (Part 1)
By naomidlynch
Understanding Silicones: The uses of silicon in FX; Tin vs Platinum; Behaviours and Applications.
First point, for anyone who isnt sure, Silicone, the synthetic polymer, is correctly spelt with an ‘e’ on the end, to distinguish it from the metalloid element, Silicon. Technically, it is a misnomer anyway, that dates from their discovery in 1942, it was thought the structure of the compounds was similar to ketones, when they are in fact Siloxanes. However the name Silicone has become accepted and persists to this day.
Right, that’s out of the way, now to business…..
What is Silicone?
Here is the Wikipedia definition: http://en.wikipedia.org/wiki/Silicone
The Encyclopaedia Brittanica explanation:http://www.britannica.com/EBchecked/topic/544410/silicone
and for the real chemistry nuts, Dow Cornings spiel:http://www.dowcorning.com/content/discover/discoverchem/properties.aspx
Does any of that help? Well, maybe, but it wont necessarily help you make that mould/art piece/prosthetic or the like….
Basically, silicone, for our purposes, is a synthetic polymer, which sets, or vulcanizes, at room temperature, into a rubbery material. This is known as RTV Silcone. It comes in hard and soft formulations, is inert once cured, heat resistant, flexible (even in hard kinds) and very very useful! RTV silicone rubber is used in the movie, entertainment and special effects industry, and in theme parks. Soft “skin” silicone rubbers, used by make-up and Fx artists, were developed specifically for sfx makeup artists, and certain kinds are also used in the medical prosthetics industry. It is also used, in an uncured form, as a lubricant, which will be apparent to anyone who has ever spilt uncured silicone on their floor…. it is an immediate shortcut to the kind of slide action Tom Cruise was famous for in ‘Risky Business’…..
So how do you know what kind of silicone to use? That depends on what you are using it for…. First I will go through some basic information that everyone should know before they start.
Which Silicone do I use?
RTV Silicone comes in many varieties, but the first thing to realise is that there are TWO main types. These are classified by the CATALYST used to turn the uncured, liquid, silicone polymer into a solid product. One is known as Tin Silicone, because its catalyst is a tin-based chemical, the other is Platinum Silicon. To further complicate this, often you will hear them described not by the type of catalyst, but by the manner of combination and vulcanisation (setting process). That is, Tin-based Silicones are also known as Condensation-Cured Silicones, while Platinum Silicones are Addition-Cured.
Just when you think its time to go get a nice cup of tea, or a stiff Scotch, there are even MORE differences… The Tin-based systems come in two different types –
One-part materials contain all the ingredients needed to produce a cured material. They use external factors – such as moisture in the air, heat, or the presence of ultraviolet light – to initiate, speed, or complete the curing process.
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Typical uses – building sealants, high-consistency rubber (HCR) compounds, coatings for electronics, medical bonding adhesives
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Advantages – easy to use; low- or room-temperature cure (although, in some cases, cure can be accelerated by heat)
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Disadvantages – moisture-curing materials may take 24 hours or more to fully cure; precautions must be taken to protect the material from the cure initiator prior to application
Examples include window and bathroom caulking. These silicones are NOT suitable for mouldmaking or prosthetics, though they DO have an unexpected application in painting silicone models… (to be discussed in a later post)
Two-part systems segregate the reactive ingredients to prevent premature initiation of the cure process. They often use the addition of heat to facilitate or speed cure.
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Typical uses – high-speed, high-volume operations, such as the application of silicone release coatings or pressure sensitive adhesives, injection molding of liquid silicone rubber (LSR), soft skin adhesives (SSAs) for healthcare applications
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Advantages – longer shelf life, high-speed cure (some materials cure within seconds), and the ability to carefully control bath life and cure time by manipulating the formulation
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Disadvantages – mixing required; often requires more sophisticated processes and formulating/application expertise.
Platinum cured silicones only come in the Two-part system. We will be looking at Two part systems here.
Platinum or Tin?
Both kinds of silicone have unique properties that make them suited to certain applications. For instance, if high temperatures are anticipated, then addition cure silicones (platinum catalyzed) are typically a better choice. But for economy, general mold making and prototype applications, condensation cure (tin catalyzed) would be preferable.
Condensation cure (Tin) two-component silicone rubbers are cheaper, (as far as I know, tin is still cheaper than platinum..) and better for most general mold making and prototype applications. They use Tin salts, and titanium alkoxide for catalysts. Most (but not all) Condensation cured silicones are mixed at a ratio of 1 part catalyst to ten, twenty, or even up to 100 parts of silicone! They are usually (but not always) measured by weight, not volume, and accurate scales are essential. You can add things to them like fillers, colours etc without appreciable affecting the cure.
Tin catalyst rubbers are not sensitive to inhibition, meaning they will cure at room temperature over virtually any surface. They’re easy to mix and de-air, because they have a relatively long curing time which allows bubbles to rise to the surface. The cure time can be reduced either by increasing the amount of catalyst used, or by adding special activators. *WARNING: Over-accelerating your silicon will dramatically reduce its usable life, by causing brittleness and deterioration, in direct proportion to the amount used. Tin silicone molds are excellent for casting polyester, epoxy, polyurethane, masonry, gypsum and candle wax. Tin silicones have a relatively long geltime, and a long period after gelling before they can be demoulded. Oh, and when mixing, if you miss a little bit, don’t stress, it will usually cure anyway….
Advantages
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Cost.
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Resistant to catalyst poisoning or substrate inhibition- they set over almost anything.
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Adhesion
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Versatility
Disadvantages
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Tin silicone appliance and moulds leach over time, and become brittle, as the catalyst is unstable. Because of this they cannot be used for any purpose requiring a long shelf-life, or in contact with skin.
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Tin silicone moulds cannot be used for casting Platinum silicone in. (*see note at end of article)
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Need air and moisture to cure, not good for confined spaces.
Addition cure (Platinum) two-component silicone rubbers offer superior heat resistance and cure with virtually no shrinkage. Their catalysts are Platinum, and rhodium.
Skin-safe platinum silicones (used for life-casting or appliances) are often mixed at a ratio of 1:1. Most of the mould making platinums that we use ( BJB’s 5000 series, Shinistu, or Smooth-On’s Smooth Sil series ) still require a scale. 1:1 silicones are usually (but not always) measured by weight, however some can be measured by volume.
Platinum rubbers can be inhibited by tin, sulphur or amines, in fact a whole heap of things you probably never thought about. Latex is a no-no, so you cant use latex gloves while mixing them, nitrile or vinyl are the best choice. Avoid gloves with additives and powder if you can. You cant use them on a wet surface like water-based clay without sealing it, or on plasticene sculpting products with sulphur in them, (you will need to get a Non Sulfur Plastilene, or NSP clay.) You cant use them in the same ROOM as foam latex is being made or baked in, and other airborne contaminants can also inhibit. Fresh fibreglass must have the styrenes baked out, or be left to cure for a week or so, or it inhibits…
*Hot Tip: if one is to use a platinum with a fresh polyester mould… to avoid styrene contamination, a simple misting of PVA (PolyVinyl Alcohol., sold as a release agent.. NOT PVA Glue..) will do the trick quite quickly. And being water based.. it cleans out very easily.
Adding too much or the wrong kind of pigment, accelerator or retarder, can also inhibit. However, despite their fussiness, they CAN be cured in total confinement, and the cure rate can be dramatically accelerated with heat. Finished moulds are ideal for casting epoxies, low melting-point metals and polyurethanes. They can be accelerated by adding an accelerating agent, but as they have a very short geltime in comparison to tin-based systems, you are more likely to want to slow them down. This can be done with a retarder, or simply by chilling the components before use. They also have a much shorter working time, and life-casting platinums and Platgels have a considerably shorter cure time, which can be both an advantage and a disadvantage, according to purpose. Most of the mould making platinums require more time than tin based mould making silicones to cure up. Mixing must be done thoroughly and evenly or you will be left with uncured parts, and if you are too vigorous, air bubbles can be a problem, unless you have a vacuum degassing chamber.
A comment from very experienced FX Artist and Mouldmaker Rob Freitas: “I find that many people use “skin” casting silicones to make moulds with when it comes to platinums… Ecoflex series.. Dragin-skin series… Plat-Gel series.. they are fast… and mix at 1 – 1… but at times… the end results are very soft, so it is a bit more difficult to get really tight seams with them. And also to have the silicone line up perfectly with the jackets can be assisted by having a firmer silicone as well.Also, when pouring bigger moulds… the “quicker” setting times can decrease the necessary flow time needed to fill some moulds. For simplistic moulds that do not require sufficient time to flow and fill, they do work ok. And yes, they will set quicker.. and are easier to use. The faster the silicone sets… the less time it has to be contaminated. But for a firm… tight… long-lasting platinum. The slower, firmer platinums will yield superior results in my eyes. But one has to manage the contamination issues far more closely with the slower setting platinums..”
Advantages
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Cure without byproducts and can be accelerated by heat with no loss of ‘library’ life.
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Clear, deep-section cure, no shrinkage,
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Cures in a vacuum, so good for multi-part moulds
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Texture can be altered with additives to make a ‘fleshier’ more flexible product for sfx, prosthetics and animatronics.
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Good adhesion
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Certain formulations are safe to use directly on the skin, either for moulding or for building up realistic skin effects.
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Certain formulations are used as medical adhesives, or to attach other silicone pieces, some are self-adhesive in their uncured state.
Disadvantages
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Potential for catalyst poisoning and substrate inhibition
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Catalyst cost can be prohibitive in large amounts.
Both types have a limited shelf life in their uncured state. It is not advisable to buy larger quantities than you are likely to use in that time period (usually specified on the Manufacturers information.) The “library” life, that is the life of the cured silicone varies from product to product and you should check with the factory if it is important. Just as a guideline, Tin products may last as little a matter of months (if over catalysed or accelerated) or as many as ten years, while Platinum can last indefinitely under optimum conditions.
*Note: Just when you thought it was safe… A crucial point to remember when making silicone moulds is to think ahead to your finished piece. If you need a final result made out of Platinum, then your mould will need to be Platinum, because- yep, you guessed it, Tin Silicone is one of the many things that inhibit the cure of Platinum Silicone. Conversely, Tin Silicones will set over Platinum without any problems. There have recently been a couple of products developed by one manufacturer that coat the silicon with a protective substrate, and are therefore supposed to allow use of a Tin silicone mould with a Platinum cast, but they are not yet widely available and have not been tested with all manufacturers products.
Summing up:
1. What is RTV silicone? Two components that when mixed together cure at room temperature (RTV= room temperature vulcanization).
2. What types of silicone are there? Tin-cured, (or Condensation Cure), and Platinum-cured, (or Addition Cure).
3. Tin-cured are USUALLY (but not always) mixed in a ratio of 1:10 or higher, by weight. Platinum-cured are USUALLY mixed by weight but several kinds can also be mixed 1:1 by volume.
4. Tin is cheaper, and easier to use. It is limited in application due to limited ‘library’ life and curing requirements.
5. Platinum is expensive, and requires care and attention when using. It lasts indefinitely, some grades can be used in contact with food or skin, and cures in a vacuum so is useful for closed moulds.
6. Both can be made to cure faster, but if you accelerate Tin, you trade-off the usable life of the piece. Platinum can be accelerated with heat, but remember if you decrease the cure time, you will also decrease the work time!
The How and Why of Silicone. (Part 2)
By naomidlynch
HOW TO CHOOSE YOUR SILICONE
Ok, so you have your project ready, you are off to go buy some silicone and dive right in…. Whoa! Slow down, tiger….. There is a whole bunch of stuff you need to know first.
What are you doing? Is it a big piece, a small piece? Are you making a mould or a cast? Do you need to make a box mould, a brush-up mould, a matrix mould, a pour mould? How much are you going to need to fill it? Do you want a solid coloured, or translucent silicone? Are you in a hurry or is time not an issue? Will you need a long or short Potlife? What sort of Viscosity is required? What Shore Hardness do you require in your finished piece? Do you need to worry about Elongation/Tear Strength/Tensile Strength?
Yeah, working with silicones is a bit like doing high school chemistry all over again, but trust me, if you understand the basics, it will save you a lot of time, money and frustration.
Lets start with the Product Description.
When you are searching a website for silicon moulding rubbers, you will usually find somewhere a link to a.pdf saying “Technical Data Sheet”, “Product Overview”, or the like. In a catalogue there may be aTable giving comparisons between the products on offer.
Note that the information I am discussing here is NOT on the MSDS… (the what? I hear you say? It stands for the ‘Material Safety Data Sheet’- a topic for another time…).
A Technical Data sheet will give you all of the relevant information you need about a product. Lets go through one step by step, just to give an example.
At the top there will normally be a Product Description. This will describe the general characteristics of the particular silicone, its category and type, and an idea of its texture, hardness, mix ratio and suggested applications.
Here are a couple of examples I randomly pulled out of my file (you should always keep this info for future reference):
1. “ProSkin is a two-component silicone elastomer that cures at room temperature by a polyaddition reaction that may be accelerated by heating. It is designed as a 12 Shore A high tear strength rubber providing excellent physical properties for prosthetic and orthopaedic applications. It also displays good translucency and high elongation. Proskin is easy to process with a 100:100 ratio by weight or volume and has an extremely low viscosity when mixed.
Typical Product Uses:
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Orthopaedic Applications
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Prosthetic Devices and appliances
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Anywhere a soft skin-like feel is required
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SFX skins
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Cushioning appliances”
2. “Elastosil M4503. Pourable, condensation curing, two component silicone rubber that cures at room temperature and features:
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Good flow
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Low Shore A hardness (approx 25)
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High Tear Great extensibility and elasticity
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Excellent long term stability of the mechanical properties of the cured rubber.
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High resistance to casting resins, particularly polyester
Applications
Due to the excellent mechanical properties of the cured rber as well as its high resistance to casting resin, Elastosil M4503 is especially suitable for reproducing models with pronounced undercuts in casting resinc. Other materials, such as wax and plaster, may be cast without any problems in moulds made from M4503 Skin Moulds. “
Ok, so reading through those, what do they tell us? Which one is the Platinum Silicone?
Further down the sheet we come to Product Data, both Uncured and Cured. This is where the specific scientific measurements are listed. We will go through them one at a time.
No matter the format, each information sheet should have the following on it somewhere, although perhaps in a different order:
Colour-
usually translucent, white, or for certain products, blue, pink, yellow etc… Frequently, the colouring agent will be in one part, for instance the catalyst, or one part of a 1:1 system. This assists with the even mixing of the product. Proskin is a translucent silicone, that can be intrinsically coloured for the final result. This tells you that it is likely designed for making products or appliances. M4503 is a white silicone, which tells you that it is primarily used for mould making, as are most solid coloured silicones. However, there are times when you need to have a mould that is translucent, so you can see the piece through the mould itself for various reasons.
(The one thing no-one has yet managed to do is make a water-clear silicone. Well, they did, but it turned out to be so brittle it was unusable. It has since found a perfect purpose, as a form of breakable glass, too fragile to be put in a window but great for simulating crushed or broken glass on set with no danger to actors or crew).
Density, or Specific Gravity-
usually specified as @23 or similar, meaning at ambient room temperature of 23C. Density is expressed as a measure of Grams per cubic centimetre. Specific Gravity is a ratio of the Density of a substance to a reference substance, usually water. Water can be assumed to have a Density of 1 at sea level and 20C, and if a substance has a Specific Gravity of less than 1, it will float on water.
In our examples, ProSkin is listed as having a Specific Gravity of 1.08, Cured; while M4503 is listed as having a Density of 1.16, Cured. In plain terms, this translates to both kinds of silicon being heavier than water. Silicon is heavy, and fluid, and like water, follows gravity. The practical upshot of this is that if you leave a tiny hole ANYWHERE in your mould wall, or any edge is not completely sealed, the silicone will find that hole, and depending on the cure time of your material, when you come back several hours later to check on it, a great deal will have oozed out of that pinprick, and probably all over the floor……. (A great prank to play in the workshop is to pour a thin trail of silicone leading from the base of someone else’s mould to a puddle somewhere…. don’t tell anyone I told you… ;) )
Mix Ratio-
this is not always listed as a category on its own, but will be in the information somewhere. Our examples give ProSkin a Mix Ratio of A:B 100:100. M4503merely includes the information in the table as ‘With 5% wt Catalyst T35′. Note that Proskin, a Platinum Silicone, can be measured by weight OR volume because parts A and B have been ‘Specific Gravity balanced’ (they are the same Density as each other).
M4503, which is Tin, must be accurately weighed. A good quality electronic scale measuring by the gram can be purchased from most kitchenware stores. If you regularly mix small quantities requiring less than 10 grams of catalyst, it is worth investing in a pocket scale that measures by the 0.1 grams. (In Australia try here- http://www.hydromasta.com.au/view_product.php?p=20803&id=21 or here- http://www.scalesdirect.com.au/store/weight-scales/pocket-scales/jennings-scales-high-accuracy-scale-range.html ) Some silicones are very finicky and you have to get the mix ratio precisely right or it wont set at all. Others are less so, and a rough approximation will do, but its always best to get into the habit of measuring precisely for consistent results.
Pot-life-
This is your active working time, and starts from the time you first put the components together in the container, including mixing time, then whatever is left is the time that the silicone is still fluid, before it becomes gel-like. It can vary substantially from what is on the sheet according to your ambient working temperature, most significantly in Platinum silicones. Potlife is generally shorter in Platinum than in Tin silicones anyway, though there is a wide range. To give you an example, I was working on a documentary in the NorthWest of Australia last year, the average temperature during the day was around 35-40 degrees Centigrade. In 24C temps, the silicone I was using, Platsil Gel10, has a potlife of around 6 minutes normally with a demould time of 30. In the tent I was working the heat was around 45 degrees Centigrade, and potlife was around 20 seconds, demould about 2 minutes……. Having a short work time is sometimes good, sometimes not!
Our Proskin has a very long potlife for a Platinum silicone, at 60 minutes, and the demould time is merely described as ‘variable’. The M4503 is a fairly standard 90 minutes for Tin, with a 15-20 hour Curing Time to be tack-free.
Demould Time-
This is often the single determining factor in the final choice of silicone for professionals. Have you heard of the Designers Holy Trinity? Good, Fast, Cheap. Pick Two.
If you don’t have much money, but plenty of time, use Tin silicones. If you have no time, but a great deal of money, use Platinum. If you have neither, you are in trouble.
Our Proskin comes in at ‘variable’, which can mean anything between 30mins to a couple of hours, or less if heated to accelerate cure. M4503 will take 15-20 hours before you can touch it without it feeling sticky.
*IMPORTANT: If your silicone still feels tacky or sticky, or ‘wet’ on any surface after the expected cure time has elapsed, it is NOT going to set if you leave it longer. Platinum silicone can be slower in temperatures below 20C, and faster in temperatures above, or can be accelerated by application of heat (waring the mould in the oven on 50C, or blasting with a hairdryer, or directing a fan heater on it- I hasten to say, AFTER it has reached the gel stage). Tin silicone is an inexorable process that will cure in the allotted time no matter what… UNLESS there is a problem. We will be looking at possible problems later in this series.
Viscosity-
this is most simply described as the relative thickness of the liquid. In actual fact it is a lot more complex, but for our purposes we don’t need to get into Newtonian Fluid Mechanics….. Suffice to say that Water is measured at 1 centipoise, which is one one-hundredth of a poise, and equal to one millipascal-second (mPa·s) in System Internationale Units. Honey has a viscosity of 2 000 centipoise (or mPa s) and Molasses has a viscosity of 5 000 centipoise. Lard is extremely viscous at 100 000 centipoise. Our examples come in at 2500 mPa s for the (mixed) Proskin, and 40,000 mPa s (mixed) for the M4503.
From this we can gauge that Proskin is a really runny consistency, while theM4503 is quite thick and pasty. Can you think of situations that would require a very viscous silicone, and one that would be better with a thinner, more fluid silicone? Also remember that there are Thixotropic agents that can be added to silicones in small proportions that will change the viscosity of the material, and are often used when you need the properties of a silicon that is naturally runny (maybe because it is clear and soft) but you need to make a brush-on mould….
Hardness- (Shore #)
Ok, this is the big one. Probably the single most important measurement on the whole sheet. Hardness may be defined as a material’s resistance to permanent indentation and is measured by a durometer, on a scale invented by Albert F Shore in 1920. There are several different scales within the system, but the most commonly used in silicone rubber technology is the ASTM D2240 type A scale, mainly used for softer plastics. They measure between 1 and 100, with the higher number representing the harder material. As an example, tyre rubber is between 50 and 70 on the Shore A scale, dependant on the application. This link has a great chart explaining the Shore scale:http://www.quickparts.com/LearningCenter/ShoreScale.aspx
The reason it is so important to us is that we need to know how hard our finished mould or piece will be. If you are moulding an item or sculpt with a lot of deep undercuts, you need a bendy, flexible mould, so you couldn’t use any silicone with a Shore A greater than say, 30. If you dont need to worry about undercuts and require a self supporting, rigid mould, then you would choose a silicon with a Shore A of greater than 30, and maybe even as much as 60 or so. If you are using silicone to make an item, be it a sculpt or a prosthetic appliance that will be glued to the skin, it is crucial that you know the hardness. If you are making a body part, then think- is it a flexible bendy part, or a stiff, bony part? Does you piece need to be soft and floppy, or stiff and self supporting? Choose accordingly…. Often the suggested applications will tell you what this product is best suited to. Our Proskin has an extremely low Shore A hardness, at 12, which is eminently suitable for the ideal purposes of skin-like products. M4503 is a fairly soft 25, so it is a fabulous moulding material for very detailed models with large or deep undercuts.
(*Note: SFX Prosthetics is a particularly specialised area and there are certain silicones that have been specially formulated with a third component that adds even more ‘fleshiness’ and ‘stickiness’ without affecting the cure.)
There are several other measurements that are relevant for industrial mouldmaking applications, but probably of less interest to most of us using silicones in the film industry. They include Tensile Stength, Elongation, Tear Strength, and in Tin Silicones, Linear Shrinkage and Expansion factors. We wont be going into those but information is readily available for those who are interested.
In the next part of what is turning out to be a slightly longer series than I had anticipated, we will look at using the silicones.
Summing Up- Important factors in your choice:
1. Colour- Do you need to see through your mould for careful removal of the item, or accurate placement of a prosthetic?
2. Pot-life and demould time- are you in a tearing hurry or can you afford to take time?
3. Compatibility- remember from Part 1, you can cast Platinum into Platinum, and Tin into Tin or Platinum, but you cant cast Platinum into Tin! What are you moulding, and what will your final piece be made from?
4. Viscosity- if you are pouring a matrix mould or a box mould over an intricate piece, you want runny. If you are brushing silicone over a large or vertical surface you want thick. Sometimes you need a combination of both.
5. Hardness- what does your silicone have to do? This will limit your choice to hard (High Shore A) or soft (Low Shore A) materials.
The How and Why of Silicone, (Part 3)
By naomidlynch
USING YOUR SILICONE:
So you are now fully equipped to choose exactly the right silicone product for your purpose, and you are champing at the bit to get started. So lets look at how to do that.
I’m not going to go into the entire multifaceted sculpting and mould-making process here, it would take me six months, and there are already a lot of fabulous resources out there…. (see post on My Makeup Books) what we ARE going to look at now is the actual silicone itself and what you need to do to end up with a usable product at the end.
There are several things to do before you even open the product.
FIRST, make sure your workroom, tools and materials are neither too cold, nor too hot This, I understand, can be tricky…. but especially in your first few attempts with silicone, it will make the process much smoother and increase your chances of success. (All Technical Data sheets list the estimated geltime and total curing time of your product, at an ideal working temp of around 24C (about 75F).)
Wait a minute- chances? You mean this isnt a guaranteed, easy peasy, smooth as pie process? Weeeelllll…. technically, yes, it could be, as long as you follow the instructions perfectly and work in optimum conditions. But Im not going to lie to you- there are many things that can go amiss if you aren’t careful, and sometimes, even if you are…
SECOND, assemble your tools and materials. You will need to make sure your materials and workspace are clean, and all components are compatible with the silicone of your choice- remember your list of inhibitors. You really need to have an accurate electric scale measuring by the gram for working with silicones, plus a pocket scale that measures by 0.1 grams, especially if you are making prosthetics and the likes that use only small amounts… (see The How and Why of Silicone (Part 2) for some good pocket scales). Dont forget the calculator and a notebook to write things down- NEVER assume you will remember it all. Also, you will need to make sure you have CLEAN CONTAINERS. Never try and skimp on this… as my 16 yr old observed, recycling isnt a large part of Special Effects, and although we can re-use some things, it pays to be scrupulous when working with something as fussy and expensive as silicone. You can save a container you have used for the same silicone before and remove the old cured mix, but if there are uncured parts you are best to dispose of them and start again. Some cardboard cups contain wax that can inhibit some silicones. Clean paper cups, plastic containers or foodgrade plastic buckets are best.
THIRD, it goes without saying that you should ALWAYS test your materials before starting your project. It also goes without saying that most people simply don’t bother….
Just to remind you why testing is a good idea, I have recently had a couple of people approach me with problems they have had with platinum silicone failing to cure properly, even when they had, in theory, done all the right things, and no causes were immediately obvious. Imagine if you ran a large workshop, and you were commissioned to create a large sculpture, lets say, a baby dinosaur, (around the size of a small pony). You can imagine that something that size is going to require a lot of material, maybe as much as a couple of hundred kilograms of silicone between the mould itself, and the skin of the finished piece. Oh, and it has to last, too, so it would be need to be Platinum rather than Tin silicone. Just for argument sake, we will use a base cost of around Au$70 per kilo of silicone. Lets imagine your total material cost for silicone in the mould and finished sculpt might then be as much as $14,000…. Would you just start right away, or would you do a test first? Of course you would! Yes, you have used that particular brand of Non Sulfur Plastilene for sculpting before, and that exact brand of silicone, and its never failed. Yes, you are an expert at fibreglassing, and you know better than to use fresh fibreglass moulds with silicone, and naturally you have a drill mixer and a vacuum degassing chamber. But even then- could you afford to take chances with $14,000 worth of materials?
True story- a certain large lab did indeed have a dinosaur to build, and -having done their usual thorough and comprehensive materials tests-, proceeded to make the case mould for their dinosaur. (A case or matrix mould is made by covering your sculpt with a layer of protective material like paper towel or plastic, then wet clay, then building your shell mould over the top. Once the fibreglass (or plaster) shell is set and cured, the pieces are separated, the wet clay and protection is removed, and the gap between the sculp and the case is filled with silicone through pouring holes, to produce a flexible inner mould capturing perfect detail and allowing a certain amount of undercuts.) After the allotted time for the cure had elapsed, the fibreglass outer shell was dismantled, and whoops- one particular section on the flank had completely failed to cure!!! It was surmised that an airborne contaminant must have drifted from another area of the workshop at some point and settled on an exposed area of the sculpt, where it later inhibited the cure of the finicky Platinum Silicone. As a result they had to discard the entire silicone inner of the mould, cut out that whole contaminated section of the sculpt, redo it and retexture it, and repour several thousand dollars of material. This story is not relayed to deter you, merely to inform…. ;) (See PROBLEMS)
Now before you give up and abandon silicones forever, I have a confession- I have been using silicone for years, and the only curing problem I have EVER had was trying to set Platinum silicone in a fresh fibreglass mould, resulting in a full head mask set perfectly against the plaster life-cast, and with a surface like unset jelly! (*see PROBLEMS) I managed to salvage it by stippling the surface with a very fine layer of fresh silicone which set against the jelly and provided a usable piece. As it was a zombie, the loss of fine detail wasn’t as much of an issue as it would be in a character makeup. A week later when I needed to cast the second mask, the fibreglass mould worked fine!
So, to sum up: If you make sure you have a clean workspace, at the right temperature, measure components accurately, and mix thoroughly, and your subject is non-inhibiting, then your product should behave exactly as it says on the packet!
NO TURNING BACK:
Time to mix your silicone!! Exciting!
1. MEASURE – How much silicone do I need?
Calculate the amount of silicone you will need to fill your mould. If you are a maths whizz you will already know all of this and probably accuse me of oversimplifying!! For the rest of us normal human beings, here’s the easy way. DON’T CONFUSE WEIGHT WITH VOLUME!!!!!!! Silicone is sold by weight, so to calculate the amount of silicone you need, we need to know how much (VOLUME) our mould will hold, and then the equivalent weight of material (MASS) to fill the volume we have calculated. If its water thats pretty much 1:1, but Silicone has a higher Density than water so its weight is greater than its volume. *Mass is how heavy something is. Density is how heavy it is for its size, eg a kilo of lead is small and therefore very dense, while a kilo of feathers may weigh the same but it takes up a lot more space, so it is less dense….
Use the following formula: Volume = Mass/Density, and Mass = Volume x Density, The Technical Data sheet will give you the Specific Gravity, or Density, for your particular silicone. Density is TEMPERATURE SPECIFIC, so this only works really accurately if your silicone is at or around the ideal temp given on your sheet of about 23C. As a rough guide, many things get denser as they get colder due to shrinkage. Obviously this isn’t an issue with small quantities, but in a large mould it can result in an expensive mistake.
For a small, simple Box Mould, glue your item in place on the base, (or if it is aTwo Part Box Mould, embed it halfway into clay in the bottom half of the box,) fill it with water and then measure that water to give you the volume of the mould. Multiply the Volume by the Density of your Silicone. TOP TIP: if it is a 1:1 mix, you can simply halve the required volume and mark the resulting volume on a container for each component, eg 1 litre of water gives you a half litre of each component, fill the containers to the 500ml mark and there you have it.
If you have a flat Plate Mould, for which we often use cardboard strip or wooden strips to build the sides, the water trick won’t work… but you can measure the depth, and approximate the square centimetres by measuring the sides. For example, a mould of a 30cm square board that has to cover several small flat sculpts of scars, 1 cm high at the deepest point, would be calculated thus: The dimensions of a square 30cm x 30cm = an area of 900 square centimetres. We know our mould has to be at least 5mm thick above the highest point of the sculpt, so we calculate the required depth at 1.5cm. 900 x 1.5 = 1350, or 1.35 litres.
To clarify, the AREA, (900 centimetres squared) multiplied by the DEPTH (1.5cm) gives us a VOLUME, or CUBIC CENTIMETRE measurement of 1350 cm3. A litre in volume is 1000 millilitres or 1000 cubic centimetres or 1000 m3, therefore our required volume is 1.35 litres. Multiply the SG of your silicone by the volume, lets say you are using one with a Relative Density, or Specific Gravity, of 1.16. You would have a Volume of 1,350 cm3 (1.35 litres) x Density of 1.16, giving a Mass of 1.56kg. You need to use 1.56 kg of silicone to fill that mould. TOP TIP: If you have an old cured piece of a similar silicone of the right thickness sitting around, you can always have a rough guess how many of those pieces would cover the area of your mould, weigh the piece, multiply the number by the weight and that will give you a good guide.
If you have a Matrix or Case Mould, take all the wet clay you used to cover the sculpt and build your shell over, stuff it into a bucket of known volume and then use that to approximate the volume. Alternatively, measure the weight of a known volume of clay (say 1 litre), work out the weight ratio between the clay and your silicone, and use that to calculate the equivalent quantity of silicone.
If you are making a Brush-up Mould it’s a little trickier and will be a guesstimate at best, but remember you can always add more layers and build up your mould as you go. You should also use an unthickened surface layer first to capture the fine detail in any case.
And so on and so on….. you get the picture.
“But Im not making a mould, I’m taking a Lifecast… “ Each of the special Skinsafe Silicones that are designed for bodycasting will have information on the manufacturers website listing the approximate quantity needed for various bodyparts. Be especially careful with these silicones as temperature has a HUGE effect on their setting times and that can really mess you around. If you mix up too much and it sets before you get it on that’s an expensive waste. Best to do a thin layer first then mix another batch and add a second layer.
Once you know the Volume and have worked out the Weight (Mass) you need, weigh out your components in the correct ratio. If your silicone is a 1:1 ratio, then halve the total volume and measure each half separately in a clean container. If your silicone is a ratio of, say, 1 part Catalyst :10 parts Silicone or higher, calculate the weight of each part by adding the TOTAL PARTS of silicone (1:10 = 11 parts total, 1:100 = 101 parts etc) and then dividing the required Mass by the number of parts. E.g. For a mould needing 2.4 kilograms of silicon, if you are using 1:1 silicone, that gives 1.2kg of Part A and 1.2kg of Part B. For a silicone with a ratio of 1:100 (10gms for every 1000gms or 1ogms per kg) you will need 2400gms/101 = 23.76, so that means 23.76 gms of Catalyst to 2.376gms of Silicone. Got it?
ADDITIVES:
Pigments- Many mouldmaking silicones have a clear or white part and a coloured part, which helps in mixing. When you are using a translucent silicone you may want to add pigment for the same reason, and if you are making a final piece, you will often want to colour it. If you are adding pigments follow the recommended instruction as to which component to add it to, and mix thoroughly before combining your components. Be sure to follow recommended ratios to avoid inhibition.
Retarders/Accelerators/Thixotropics – Accurate measurement is crucial. Thorough mixing is also crucial. FOLLOW INSTRUCTIONS CAREFULLY!!
2. MIX – How do I mix my silicone?
One particular manufacturer has the charming recommendation on its product information that if you intend to mix your silicone by hand, they recommend three or more years of experience as a commercial cook first!! They arent kidding….. although Tin Silicone is pretty forgiving, and a few unmixed streaks will probably cure regardless, Platinum is much more finicky and must be thoroughly combined. The recommended methods for mixing are similar for both kinds, but the major determining factors of method are your POT LIFE and VISCOSITY. (See The How and Why of Silicone (Part 2).
An important thing to note when mixing silicone is that if you mix thoroughly and vigorously like you are supposed to, you will get loads of air bubbles in the material. The thicker or more Viscous your material, the easier it is to make bubbles!! This is not good, as those bubbles can stick to the surface of your sculpt or model, and also weaken the structure of the mould. If we get bubbles in it, they need to be removed either before or during the pour (see 3. POUR). Platinum silicones with a very short potlife must be mixed very carefully because the silicone will likely gel before the air can be removed. People who do a lot of large silicone pours will do well to invest in a Vacuum Degassing Chamber, which creates a negative air pressure around your mix and ‘sucks’ the air out of the silicone, but if you are reading this, I am going to assume that either you don’t have access to one, or if you do you wouldn’t know how to use it anyway, so we will look at other options here.
MIXING BY DRILL- If you have to make a large mould or item, you will need to choose a silicone with a LONG POTLIFE. This is essential because it will allow you to mix thoroughly and still have time to get the air out. I recommend a drill mixing attachment- there are a couple of different kinds you can get at the hardware store that attach to your electric drill and are designed for paint stirring, they rotate and work kind of like an egg beater. You also want one with a fairly low VISCOSITY because it is easier to pour. Once you have thoroughly stirred the two halves of your mix, scrape the sides down and make sure you havent left any unmixed material in the corners of the base of your container, then mix it again!! Now you can let it sit for a little while, no longer than about a quarter of the time of your potlife (not including mixing time) to allow bubbles to rise towards the surface.
MIXING BY HAND– If you are making a smaller mould you can use a shorter POTLIFE, and you can use a hand method like a paint stirring stick, or with very small amounts even the disposable flat wooden spatulas…. Using a figure eight motion combine the components and take care not to ‘beat’ but to ‘fold’, so as not to incorporate too much air. Scrape the sides and the base of the container thoroughly every few stirs. Always mix as much as you think you need, then do it again, just to be on the safe side.
3. POUR – How do I pour my mould?:
You have your model, sculpt or item, and you have chosen your mould style.
Important point to remember– silicon is dense and heavy. It will follow gravity. It has a particularly alarming tendency to find any pinprick gap in your mould wall or casing and ooze out. It also finds the lowest point in any situation and pools there. Which means that if you do not take steps to anchor your object, cast or item very, very, thoroughly to the base of your board, (superglue works well)…. you may find that instead of the silicone covering your object, even a heavy item will instead soon be floating on top of the silicone!!!
To pour a Box Mould or Plate Mould, this is the best way to remove air bubbles and cover evenly. Place mould on a level floor. Stand on a chair. Hold mixing container carefully as high as you can without spilling it, andVERY SLOWLY pour a very thin stream of silicone so it pools in a corner of the mould, preferably not directly onto your sculpt. This allows the silicone to rise up over the sides of the piece, pushing any air bubbles away from it and finding its own level. As the silicone stretches, the encapsulated airbubbles will stretch and burst so that the silicone hitting your mould has very little air in it, and hopefully those bubbles will find their way to the surface easily. TOP TIP: Be aware that if you have significant undercuts, you may need to do at least part of the pour with the mould at an angle to prevent the air bubbles being trapped under overhangs. Once you have finished the pour, transfer your mould to a safe (level) place like a tabletop, and bang carefully underneath the table to encourage air to rise. If you are using a transparent or translucent silicone, and you can see airbubbles on the surface of the sculpt, you can pop them with a popstick or a gloved finger. Then blow gently on the surface from time to time until it has gelled, to pop any emerging bubbles. You can use a straw to do this for directed effort….
To pour a Matrix or Case Mould, you will have left holes in the hard shell mould for filling, and also placed small holes in undercuts for air to be squeezed out. Normally you would use either a funnel and do the same trick as the flat mould, that is, pouring from a height, slowly, or if you are using a thicker silicone, it is possible to make a syringe type arrangement, either by using a clean, unused Foam Latex Injection gun, or improvising with a large Drain Plunger. (As long as you can get pressure, and there is nothing in the plunger like a latex rubber seal that could inhibit the silicone, it will work). As the silicone starts to reach the airholes and ooze out, plug each one with a screw and keep pouring till you reach the top of the mould.
Brush-up Moulds, as the name suggest, use a thicker silicone and you simply brush on layers until you have an adequate thickness over your surface. Usually you would use a thin silicone first to capture detail, and just keep scooping it up and pouring it back over the top as it runs down the sides, until it begins to gel. Then you can apply a thicker layer, either using a special silicone designed for brushing or by adding a Thixotrpic Agent appropriate for your silicone.
WARNING: not all silicones can be effectively thickened, and some only work with their own specially composed additives. There are different Thixotropic Agents for Platinum and Tin silicones. Dont mix them up. Some silicones thicken a lot, others hardly at all. TEST TEST TEST!!!
PROBLEMS:
Oh-oh, I Don’t Have Enough Silicone and the Store is Closed, Can I Mix Two Different Kinds? – You cannot mix different types of uncured silicone. Each is specially formulated to give a specific result and wont work correctly if you mess with that. You can however add another layer on top of the first once it has passed the gel stage, and the silicone will bond quite happily, as long as you remember that Tin on Platinum = :) and Platinum on Tin = :(
Oops. My Silicone Hasnt Set – There are different types of inhibitions. If the contamination you have experienced is classified as ‘minor’, it will be ‘tacky’ or ‘wet’ looking, and only on the surface. If it is really like unset jelly but only on the contaminated side, that is ‘serious inhibition’, and ‘very serious’ would be if it is still semi-liquid or not setting anywhere.
Sometimes it means there is something in the clay, or the object you are moulding, but if you had done tests you wouldn’t have had this issue. ;)
If it is something added in the course of sculpting the clay thats trickier. Interestingly in one products info page I found this
“Residual solvents or monomers that may inhibit cure:• Chlorinated hydrocarbons that contain amine stabilizers• Alcohols– Ethanol, methanol• Esters– Ethyl acetate, vinyl acetate•Compounds with unsaturated bonds”
Those are known as ‘ temporary inhibitors’, which means once they evaporate out they do not affect the cure, as opposed to permanent inhibitors which cannot be gotten rid of. Sometimes if you havent let the solvents evaporate completely from your sculpt this may affect the cure, but if you leave the mould for a few days it can sometimes still set properly, eventually, as the solvents disappear…..
“Residual solvents that do not inhibit cure include Nonchlorinated aromatic and aliphatic solvents– Toluene, xylene– Hexane, mineral spirits”.
Stuff like Lighter fluid and Naptha therefore shouldn’t cause problems, but isopropyl alcohol can.
I also recommend covering your sculpt between working sessions, to avoid the chances of any airborne contaminant landing on it. (Remember the dinosaur..)
If the room temperature is cool, that can interfere. Low temperatures in itself wont stop curing, it just slows it down. A rule of thumb I remember from somewhere was that every ten F below 73 doubles cure time. Which means every 5-6C below 23C will double cure time, however you can blast it with a dryer or heater once it has gelled to stop that, or even rig up a ‘hotbox’ under a coffee table or large box to give it a warm environment.
Years ago when silicone first came into FX use there weren’t any room temperature catalysts and they had to use heat to set it. Even when they invented the RTV process the guys in workshops couldnt get platinum silicone to kick at all in their workshops because of all the latex they used and the foam latex they made- the air was fullI of ammonia and sulfur…… (In factories and large workshops these days they use industrial filtering equipment to clean the air of any gaseous contaminants to stop problems)
How Do I Fix It? – If you didn’t do a test, you went ahead and poured your mould, and a Platinum Silicone doesn’t set against your sculpt the first time, you have a couple of choices. Uncured silicone is notoriously difficult to remove. You may be able to remove the majority by using an absorbent material, beginning with paper towel and ending with talcum or fullers earth. Then once you have removed all you can physically, you will need to resort to cleaning agents, the gentlest of which is 99%isopropyl alcohol, and the stronger of which is Naptha or Lighter Fluid. All require good ventilation and breathing protection. All solvents will damage the surface of your model if it is a sculpture made in plastilene. IF you can adequately remove the uncured product from the model, you may be able to try again. Retexture your piece. Seal the sculpt THOROUGHLY by using a couple of fine coats of clear lacquer or similar, which will inevitably result in some loss of detail. This MAY solve the problem, but dont go and pour a whole new mould before testing a small patch. If you can’t bear the thought of resculpting from scratch, you could try using a Tin silicone for the mould casing, and then make a plaster positive, which you can then remould in Platinum silicone. Still- test first!! A long process, but take note- it is also the only way to work if the item you are moulding is itself made of something incompatible with Platinum silicone. Your other option is to start from scratch and TEST TEST TEST!!!
Unfortunately I couldn't find section 4, but section 5 is all about silicone painting, which is really helpful.
The How and Why of Silicone. Part 5
By naomidlynch
Alright, its been a while coming, but here as promised is the section on Painting Silicone. And yes, I know this says Part 5, and Part 4 isnt up yet, so you may think I’m jumping the gun, but Part 4 is going to deal with seaming and finishing techniques, as well as some interesting manufacturing tips, so bear with me and I’ll get there eventually!!
There is a lot of information here, so read carefully.
Each section has a “WHAT” describing which products we use for each purpose, followed by a “WHY” we use that and not something else, and then finally the all-important “HOW” to do it.
The products available to you will vary according to your location, and you may not have access to a particular thing, but you should be able to find the information here to help you make the most of what you CAN get.
Materials are expensive, so to avoid costly mistakes it is best to research your materials well and talk with your local distributor as well. They are there to help, and have a vested interest in getting you to come back and spend more money with them, so they will (usually) try to be helpful!
IMPORTANT NOTE ON THE INTRINSIC COLOURING OF SILICONE:
The best paint job should complement the colour of your silicone, not completely hide it. Painting silicone isn’t like painting foam latex or latex, where you are starting with a very unnatural flat dead appearance and trying to bring it to life. In fact there isn’t a lot of point using silicone for pieces if you aren’t going to take advantage of the very flesh-like translucency it inherently possesses. So the crucially important step is to tint your piece intrinsically before you cast it, to give your piece the best and most lifelike tones onto which you can then paint your ‘skin’ surface.
Either use proper silicone pigments, and flocking, or a mixture of both. You don’t want it too transparent, nor totally opaque. Think about the piece you are making and about the real object, and try to match that amount of light permeability. For instance, your hand is pretty translucent when held up against a very strong light, your arm less so, and a head, with its internal skull, barely at all.
You can use oil paints, but test first- some colours change as the silicone cures, and some react badly and inhibit certain silicones. You may be better to just buy a silicone pigment, its not going to cost much and a little goes a looooong way… You can also just tint the skin of the piece, stippling or brushing that into the mould, and then backfill with plain silicone.
You can use flocking on its own, which is one way of adding colour and breaks up the ‘flatness’ of a pigmented piece, and is a cheap-ish way of intrinsically coloring silicone dependant upon the size of the piece.
In terms of colour choices, avoid anything with orange tones. You’ll fight against them later when you do the extrinsic painting. Go pinkish or pale reds. The best “off the peg” flesh tone Neill has recommended is a Liquittex liquid acrylic colour called “Sandalwood”. Obviously you cant use acrylics in your silicone but if you can use that as a reference colour to get or mix a pigment to match that, then you’ll be off to a good start.
To achieve a realistic translucency, until you are familiar with the process you should either test small samples as you go along, just 20gm batches at most, by catalysing them and placing them in your mould or a similar mould so you can see the final result with the surface texture.
When mixing the pigment into the silicone you can use a wooden mixing stick with a small black or blue dot or vein pattern drawn on. As you mix you dip the stick in and let the silicone drain and see how the dot or lines are showing through. If they’re crystal clear then you’re way too translucent, if they’re invisible then it’s much too opaque. If you can see the dot or line but its very soft then that’ll be just about right.
PAINTING SILICONE PIECES:
WHAT MATERIALS DO I NEED?:
1. A SILICONE BASE or CARRIER
Your options are:
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Dedicated silicone painting systems
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Silicone caulking,
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One-part acetic-cure silicone.
A dedicated silicone painting system comes with a two-part silicone base system and custom pigments. Examples include Fuse FX, and Psycho Paint. While these certainly work very well they are expensive and you may not be able to afford them when starting out. Also, they are both platinum based so you can ONLY use those on platinum cure (addition cure) silicones, NOT on Tin silicones.
Silicone caulking is sold as window or bathroom sealant. In a long cylindrical tube that is usually used with an applicator. It is a single component Tin silicone that cures by exposure to air and moisture by acetic acid reaction, and it “bites” into the surface of your piece much better than using a two-part silicone mix.
One-part acetic-cure silicone is the clear leader and industry favourite. What you want is the type of silicone in a small tube from the hardware that is used as a sealant or adhesive and sometimes known as gasket silicone. It is a single component air-and-moisture activated Tin silicone like caulking, but it has a higher proportion of acetic acid so it bites better and sets faster. Popular brands are ‘Dow Corning 734 all purposes silicone glue’, ‘Wacker Elastosil A07 Flowable Adhesive’, ‘3M RS Silicone Rubber Compound’, “GE 1200 clear”, “Smooth-on Silpoxy” etc. Also use a decent quality silicone sealant. Cheaper products will always give results equivalent to their price.
*Both Silicone Caulking and Silicone Adhesives can be used on both Platinum or Tin silicones.
WHY CANT I JUST USE THE SILICONE I MADE MY PIECE WITH?
It is certainly not totally impossible, under ideal conditions, to get a half-decent finish using a two-part silicone such as you already used to make the piece, but it is definitely more difficult, because you are adding other components (pigment and solvent) which can (and will) interfere with the setting and bonding.
2 part systems (eg Platsil Gel 10, Dragon Skin, Eco Flex, etc.) use a catalyzation chemistry to cure. They’ve been especially formulated to crosslink, which means that the molecules in each part interact as soon as they make contact with the other component and over time they ‘set’. If you introduce foreign elements or the conditions aren’t right, those molecules never get to grasp each other properly, and you have sticky tacky unset jelly.
There is more flexibility and room for error when using a dedicated painting formulation, or a single component system. They will adhere better and dry faster with less risk of delamination. Caulking and silicone adhesives are an acetoxy cure system, so what happens is that the moisture in the air reacts with the solvent in the wet adhesive as it evaporates, which forces the molecules to lock together. Both caulking and silicone adhesives have a very distinctive ‘vinegar’ smell, which is the acetic acid in them.
2. PIGMENTS
Your options are:
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Silicone Pigments
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Oil Paints
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Inks
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Acrylic paints
Silicone Pigments are designed to colour silicone intrinsically, and are unlikely to inhibit your cure unless used in too-large quantities. Remember though that pigments are NOT silicones themselves and will NEVER cure on their own. They MUST be used in a base. There are some that are better for painting than others with better colour choices and more realistic shades for skintones. Mouldlife make a great selection. They may seem pricey but a little goes a long way. Be careful not to dilute the silicone too much- it’s easy to end up with mostly solvent on the brush when you mix the pigment in and end up with a mix of solvent and pigment, which will never dry completely….
Oil paints ore ok and commonly used, but, oddly enough, oil paint can have oil in it! Also there are other impurities that can inhibit the cure. Be aware that even within the same range there are different minerals used for pigments that can affect setting, and some that react strangely to silicone and actually change colour. Use too much, or too much of the wrong color and you are back to goo… Some cheaper oil paints are not going to give a good result, always try and get a reputable brand. Also oil paint on its own will set, but veeeeeerrrrryyyyyy slowly, (think days and weeks, not hours..) and it will not bond to the silicone on its own. The way to avoid this is make sure you don’t use too much solvent when painting, or you end up with no silicone in the mix and just a smeared mess of wet oil paint on your surface instead.
Inks can be used in some cases, mostly dependant upon the final use of the piece. Skin Illustrator inks are used on Super-Baldies encapsulated silicone pieces and also can be used on straight silicone pieces that are going to be used only on the body and painted in situ, as you cant use toxic solvents near a person. FW Inks are popular to airbrush over Silicone. The way to have those colors permanently fixed is to seal it with one part Silicone caulking thinned down with a fast solvent, such as Heptane, between each one or two ink colors. Bluebird Inks can also be used for intrinsically colouring the silicone, and surface painting in the same way as FW Inks.
Acrylic paint is a last resort. It can have odd effects on the silicone and make it ‘curdle’, so if you have to use it test test test! Also it WILL SPEED the cure time of silicone caulking so may require a thinner to counteract that. Best avoided.
3. SOLVENT
Your options are:
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Petroleum Distillate of some type.
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D-Limonene
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Dow Corning OS-10 fluid
Petroleum Distillates have been used as industry standard for years, but require special precautions for use as they are amongst the most toxic things we use. Proper Personal Protective Equipment is mandatory. It will, very literally, put you in hospital if you fail to wear adequate respiratory protection.
The family of petroleum distillates, or hydrocarbon condensates, includes many different chemicals- make sure you look for the ‘UN number’ on the bottle. It will be a clear chemical, and have ‘flammable’ written on the bottle or tin- basically anything with an N number (Hazardous goods identifier) between 1200 and 1300! Naphtha is UN1268, as is some liquid lighter fluid and some white spirits.
There are numerous different types with different names in different countries and from different refineries. They are sold in hardware stores and automotive stores as fuels, cleaning or degreasing fluids, or car panel wipe.
Essentially it will always have a red label saying FLAMMABLE 3 on the bottle somewhere. May be called: petroleum ether, petroleum spirits, ‘Coleman’ brand stove fuel, ‘Zippo’ brand lighter fuel, mineral spirits, paraffin, benzine, hexanes, heptane, ligroin, white oil or white gas, painters naphtha, refined solvent naphtha and Varnish Makers’ & Painters’ naphtha (VM&P)
To say it can be terribly confusing for people in different countries trying to find the local equivalent is the understatement of the year!!
For instance, ‘Naptha’ is often referred to as the preferred solvent, but ‘Naptha’ is a generic description rather than a brandname, and for instance, in Australia, it is labeled as “Shellite’ (after one manufacturer), or White Spirits.
‘Zippo’ brand lighter fluid is widely available, and is basically pure Naptha, however it’s a mixture of a heavy and light weight Naptha distillate, which allows it to be less susceptible to evaporation than some forms.
Regular White Spirit takes forever to dry. Use LOW ODOUR white spirit which is a lighter grade of Naphtha, it’s purer and faster drying.
As you can see, ‘Naptha’ can be a misleading ingredient to find on the side of the bottle. It is often used in a paint shop, but the preferred type there would be VM&P (varnish makers and paint) grade Naptha.
*We recommend you DO NOT use older solvents such asToluene without the best protective gear available. It is highly HIGHLY toxic and needs special safety gear.
ALL solvents should only be used while wearing respiratory protection classified for the solvent you are using, and other appropriate PPE.
NON TOXIC ALTERNATIVES:
For many reasons there are situations where you either cannot use a toxic volatile chemical, perhaps for OH & S reasons, or location, and in some places you cannot even buy them easily. They are difficult to transport, and hazardous to store, and if you already suffer from any health issues (or if you wish to become a parent in the near future), they may be best avoided wherever possible. If you are looking for a non-toxic alternative for safety or personal health reasons, you are in luck!! Unlike people working ten years ago, we now have a couple to choose from!
D-limonene is a far less toxic alternative solvent, and is available in many countries in hardware stores or specialist cleaning supply houses. It is classified as GRAS (generally regarded as safe) and non-toxic and is pleasant smelling. It is derived from citrus peel. D-Limonene is often used as a degreaser and cleaner, it is also used as a flavouring agent and can be purchased in food-grade qualities. It is suitable for use in smaller spaces and if you don’t have a properly vented paint booth,
Dow Corning’s OS-10 Fluid is a totally volatile organic compound free ozone-safe compound that can be used for a variety of applications. Non toxic, colourless, odourless, and safe if you have to work in an enclosed space without adequate professional ventilation systems. Works on both tin and platinum varieties and dries to such a minute thickness that it still shows every detail of texture. Works on just about any of the silicone systems. Low smell, quick drying, and you can also mix oil paints in to caulking and thin it with the OS-10. In the States Burman Industries supplies it, in the U.K. tryhttp://www.ellsworthadhesives.co.uk/index.php/dow-corning-fluid-os-10-2-8kg-clear.html They also make one called OS 30- the number represents the speed in which the solvent flashes off and out of the silicone itself, which may be useful if you are doing a bigger project such as painting a creature suit with silicone that was intrinsically colored. Hypothetically the 10 should flash in ten minutes and the 30 half an hour more or less, according to ambient temperatures. You can also use it as a thinner to to spray silicone through a spray gun like you would Super Baldiez… or an air-brush There are some primer measures and steps involved, but the OS series has also been used by people to help coat big foam latex creatures and such with tin silicone…
An alternative option is ‘Silicone Solvent’ from Reynolds Advanced Materials/Smooth-on. It is the same or similar formula, consistency, and results.
*Isopropyl alcohol and acetone are NOT suitable solvents.
HOW DO I USE THEM?
Explanations are great but they can only go so far. For some of you it is undoubtedly going to help enormously to see someone demonstrate the technique before you attempt it on your precious work, which you have struggled and slaved over to get to this point. You don’t want to come this far only to mess it up now!
There are a couple of great tutorials available online, they are both paid access to stream the video, and you can also purchase a DVD if you prefer.
Both are well worth the small price to ensure your success:
Neill Gorton has a great instructional demo here:
Also Stan Winstons Studio demo:
https://www.stanwinstonschool.com/videos/silicone-painting-realistic-flesh-tones-vol-1
1. CLEANING & PREPARATION
In a perfect world you want to paint your piece as soon after casting as possible as the fresher the silicone the better the bond. Also make sure the surface is very clean and dry. Technically the process of painting silicone is laminating, as you are applying layers of silicone on top of the piece itself, and those layers bond to and become an integral part of the piece itself. This differs from true painting in that it is not a separate surface layer that can be removed. As with all lamination, the colouring will only stay on if you have cleaned the area thoroughly of any remaining release agents, sticky fingers, dust or airborne contaminants. You want to wash your piece with warm soapy water after de-moulding, then give it a good clean with 99% Isopropyl Alcohol. Allow to dry thoroughly.
That should be all you need to do.
If however your piece has been sitting around in the open for a while or you have used a particularly stubborn release agent, you might need to bring out the big guns. (This also applies if you have attempted to paint it before you read this information and it was less than a success!)
Your first attempt should be a quick but thorough wipe with acetone and then a quick wipe with Naptha or lighter fluid, which dries without a residue. Finally, do a 99% Isopropyl Alcohol wash and it should be clean as a whistle.
If that doesn’t work for some reason, you can move up to Heptane, which is much stronger, and is available as rubber cement thinner in good art shops. Mixed 10:1 with silicone adhesive this primes the surface, and it will stick over almost anything, it dries relatively quickly but a heater in the room if its cool speeds things up. Then when that’s dry you can do a layer of the ‘normal’ silicone sealant and naptha/lighter fluid before painting and it all should stick nicely.
If you don’t have Heptane or would prefer not to use it the other option is to do a thorough degrease of the silicone with acetone IMMEDIATELY before applying the first layer of paint. *In the ‘bad old days’ they used to use the deadly methylene chloride for this; it would swell up the silicones’ “pores” and then trap the paint as it “swelled down”. It also was a powerful degreaser, could be used to thin the caulk, and also causes death and disability, not to mention the odd birth defect. No longer recommended and hopefully no longer available!!
Regardless of cleaning, to guarantee success it is always a good idea to applying a thin layer of silicone base mixed with your chosen solvent, and no colour. This gets stippled on first (use non-latex sponges for this) and allowed to dry thoroughly, preferably overnight. Your subsequent pigmented layers will stick better to this preparatory layer than to the base silicone.
2. MIXING
Mix your colours in your chosen pigment (oils or silicone pigments) separately onto a lid or in a palette (not into the silicone carrier).
You can premix some of the silicone base with some of your chosen solvent if you are airbrushing, and store in an airtight container, or you may prefer to mix a little at a time in a small container as you go and use it with your chip brush. Remember that as soon as you expose the silicone to the air it begins to react so don’t make up larger quantities than you can use in a few minutes. Likewise, solvents flash off quickly, which is a desirable quality when applying the paint, but not so great if you get distracted for five minutes and come back to find your solvent/silicone mix is now simply partially gelled silicone!!
Load the brush with solvent/silicone mix, pick up a little pigment/paint on the brush and mix it into a puddle on a palette, then flick or spatter it onto the piece. This way you can test translucency and pull the right amount of colour into the mix.
Don’t try to mix the right tones right into the silicone or in large batches, or you will waste time and money, because the solvent will flash off before you are ready
WEAR APPROPRIATE PPE!!!
Acetic Acid is corrosive and will irritate your skin, even if you are using a totally non-toxic solvent. If you are airbrushing this goes double- ALL airbrush particles are capable of causing serious lung problems if inhaled, even water, so wear a proper respirator at all times.
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3. APPLICATION TECHNIQUE:
Your Options are:
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Spatter using a cut down chip brush.
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Airbrush
Using brushes or sponges to paint directly on the surface can ‘muddy’ the colours together. It’s better to have as little contact with the surface you’re painting as possible to avoid lifting colour back off… A gradual build-up of flicked-on translucent shades with a brush or airbrush speckle should give a random natural-looking skin tone. Avoid using thick or heavy layers or you lose all of that lovely silicone translucency.
You need to work in layers, one colour at a time, letting the previous layer set up before doing the next. It actually takes quite a while to fully cure so avoid doing any abrasive action on the surface, such as using a coarse brush or sponge, with more solvent before completely dry
Spatter technique:
The good old spatter technique- exactly the same as you used in kindergarten!! You just cut the bristles down on some cheap brushes and spatter your paint on.
You want quite a translucent paint for this, so that you can barely see any obvious drops on the surface- it is the amount of opaque paint you use which will make something opaque – not the means of applying it.
Airbrushing:
Airbrushes are great, especially for misting and blended, graduated colours. so long as the amount of pigment being applied at any one time is small, then it won’t look like blotches of hard colour. Thin the pigments to the point that if you can easily see the colour as it is applied then you have too much pigment in there. It’s more arriving at the correct opacity through multiple layers rather than hitting it too hard accidentally with a thick dose of colour.
Airbrush colours need to be thin enough to go through the nozzle anyway, but you could take that same mix you would put through the airbrush and apply it with conventional brushes to get the same coverage.
The art of airbrushing onto silicone is actually to get it to spatter and spit rather than applying a smooth film of colour. If you aren’t already an expert in using your airbrush and manipulating the nozzle to achieve different patterns, then this is probably not the best time to try and learn.
4. COLOUR:
Painting silicone is more like using watercolours than oils, you want layers.
Don’t try and get one colour that matches skin. Skin isn’t a solid tone all the way through. The tint you have put in the silicone when you cast the piece will greatly influence the end result. Have a play with some little test pieces to see what I mean. A very translucent silicone mix will be harder to make look real.
Look at your hand- it looks solid, not translucent.
Now think of holding your hand up against a strong light- suddenly it is translucent, and it looks red because of the underlying blood. Yet when we shine a strong light on top of the skin it appears solid again and much paler…
So bearing that in mind, the base colour of the silicone should generally be warmer (redder) than your paint job. Also, try mixing your base paint for the first coat with a hint of green IN the mix rather than trying to get a pinky ‘flesh’ tone- practice by trying to match your own skin, it will surprise you how much green/blue skin actually has in it!! It counteracts the orange and gives a more realistic flesh tone. THEN you go over with what might seem strong colors, but very diluted- blood red, freckle brown, warm yellow, vein blue and green…. All the different colours that can naturally be found in skin. If they are very translucent you get a lovely pointillist three dimensional effect… Same for veining, use what seems a very bright or strong blue-green but dilute it greatly.
Just remember to wear a mask, safety glasses and gloves when painting- these solvents are strong enough when you’re leaning over the work, let alone when airborne!! .
Here is a basic formula for colour application, just to start you off, (courtesy of Valentina Visintin). The colours are fairly standard paint colours, so even if you don’t have those exact ones you can get a paint chart and figure out the next closest alternative.
Alizarine crimson or a similar dark blood red colour, with a hint of cerulean blue or sap green added, which will give the skin warmth.
You can sponge this over creases so it sits in the wrinkles, and give a gentle spatter. It should be very weak and translucent –not bright at all.
A warm tone next, you can use Yellow Ochre with a hint of Burnt Umber. General spatter.
Olive green on its own or with a hint of raw umber. General spatter
Purple madder with a hint of cerulean blue and sap green. I come back to blush and to increase the reds.
Vein tone mixed up with: white, cerulean blue, yellow ochre and a hint of ultramarine blue. Brush on and dab off veins.
For blushing, or on older faces, rosacaea, a mix of crimson red and cerulean blue as a blushing.
Burnt umber on its own and/or vandyke brown. You can start painting moles or freckles and come back with a super translucent spatter.
Add any desired last effect like beard shade (with payne’s grey) or increase wrinkles and shadowed areas.
Make sure you always use very translucent shades- you can always add more but you cant take it off!!
Don’t apply too heavily or the colour will drip and run before it dries. Likewise, make sure to allow adequate drying time in between layers or you will end up with mud.
At the end you may want to airbrush or sponge on a sealing layer of pure solvent mixed with silicone, no pigment. Be very careful not to disturb the paint underneath while doing this.
POSSIBLE PROBLEMS YOU MIGHT ENCOUNTER:
CURING TIME SLOW?
If you are finding that the ambient temperature or lack of humidity in your working area is making your paint take ages to dry, there are a couple of things you can do to speed up the cure.
Silicone caulking begins to cure when it comes in contact with moisture in the air. It normally takes about 24 hours to be totally cured, although it will appear touch dry before that. In cooler temperatures or areas of low humidity it can take up to 48 hours. If you live in a very dry climate you may even need a humidifier in the room, or to spritz the surface with water occasionally.
To speed up curing even further, add some glycerine to the mix, as glycerine is hygroscopic (water attracting) and it works like a catalyst.
Some people suggest water, but glycerine will be easier to mix into the caulking. Suggested proportions no more than 4-5pts silicone to 1pt glycerine. If you find the glycerine affects the texture too much, try adding a very small amount of cornflour to reduce the greasiness
SILICONE INHIBITION?
Occasionally you can have unexpected issues. A piece may be made using exactly the same brand of materials you normally use without issue, but maybe it wont set at all, or it starts out acting like it wasn’t going to set, stays pretty tacky for several days, and then finally, reluctantly, sets.
The most common issues are when people accidentally thin the caulk too far and it is basically just a layer of paint or pigment with no silicone binding agent which then cannot dry.
It can also be something to do with whatever you are using to pigment the caulk. If its oil paint there can be issues between different brands or colours, or an issue with a particular batch inhibiting the mix. It can even be the caulking manufacturer changed the formulation in some way. Brands that worked for years can suddenly stop working for no apparent reason. The only thing we can put it down to is the caulk manufacturers are changing their formulas to make products more eco friendly. Great for the environment, not so great for our silicone painting. Formulation changes can be frustrating, mainly because there is no mandatory requirement on manufacturers to inform users of changes like this unless such a change alters the MSDS. It’s a common problem upstream with raw materials or precursors, and occasionally causes real issues.
TACKY SURFACE?
You may be diluting the silicone too much- it’s easy to end up with mostly white spirits on the brush when you mix the pigment in and end up with a mix of solvent and pigment, which will never dry completely…. If it is a really severe case the only way to permanently fix it is to go over the surface with a layer of silicone and solvent, preferably one as strong as naphtha, and seal in the colour…. Either stipple it on with sponge or use a pump spray to evenly disperse it.
SHINY SURFACE?
This isn’t a problem per se as much as it is an intrinsic part of the process. It is naturally going to have a bit of a sheen to it unless you have a very textured surface, and if shine does bother you or if you want a particularly matte finish here’s what you do. The idea of “matting” is that silicone always wants to cure as a smooth / shiny surface naturally. The mould you made had texture in it but the paint surface doesn’t have that advantage so you can lose a little detail here and there … so you te the uncured silicone paint layer so that the final finish is not shiny. Think of this like you would applying a bit of powder to a face to tone down the shine and then do the exact same thing to the painted tacky silicone with a very high quality make-up brush giving a slight dusting to the surface. Some even use actual powdered make-up to do this.
Matting silicone:
Your options are:
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Krylon Brand “Dulling Spray” used on artwork to bring down the shine. Spray a little on, wait a minute or two to dry and… Viola! Instant dulled surface.
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Bluebird FX matting sealer,
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Fuse Fx matting powder
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Icing sugar also works!
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To use one of the powder options: Dust the whole piece after you have sealed the paint job. Let your silicone paint go tacky and then dust on and pat gently and allow it to finish curing. You want it on the surface, so the finer the powder the finer the matte effect … you should try this on test pieces first to get the hang and timing of dusting
Timing is crucial, if you do it when it’s too wet it can get in to the silicone and make white streaks, leave it too late and it won’t work.
Allow to cure overnight, then wash off with water. The fine powder dissolves leaving a matte surface
Another alternative to mattifying agent if you have it in your kit already is a pharmacy-bought brand of “anti chafe gel”- such as lamasil, or lanacane. Almost identical to an antishine gel, but much cheaper making it good for dummy heads & props. You can also use makeup products like Mac antishine or Kryolan hd primer.
These articles are the most thorough and concise explanations i've ever read and are an invaluable find. I really wish i'd found them before my assesment, but I can certainly take away from them for level 6.
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